The invention concerns a method for routing service calls in a telecommunication network with a switching center (SSP) recognizing the service call and a control facility (SCP) controlling the service call, as well as a telecommunication network with a switching center (SSP) recognizing a service call of a subscriber (TN) and a control facility (SCP) controlling the service call, a switching center with recognition means for recognizing service calls of a subscriber (TN) and communication means for exchanging messages with a control unit (SCP) for controlling service calls and a program module therefor.
Today the public switched telephone network (PTSN/ISDN) consists of the (sub) networks of various national, regional and local network operators. In addition to the conventional service of establishing communication calls, these network operators are increasingly offering additional so-called value added services, for example the setting-up of a so-called personal call number, by which a call is routed under time control to the service customer""s desired line unit. Specific facilities of the network operator, which are integrated in the infrastructure of the conventional telecommunication network, are used to control and perform these services. The best known of these facilities are those facilities which form the so-called intelligent network (IN for short). The services which this facilitates are also termed IN services. The architecture of the intelligent network and the structure of the IN services are laid down in the corresponding ITU-T standards.
The so-called service switching point SSP and the so-called service control point SCP form the two essential facilities of an intelligent network. The service switching point SSP is a digital switching center which recognizes an IN service call and gives the service control point SCP the option to control the call. A frequent option for calling up a specific service of the intelligent network is to dial an (IN) service number. In this case the leading numerical sequence of the service number forms the service identification of a specific IN service. The service switching point SSP recognizes the IN service call and informs the service control point SCP which is resolving the service number, that is to say the determination of the physical address of that facility with which the subscriber has to be connected in order for the service to be implemented. The service then runs under the supervision of the service control point SCP. A detailed description of the tasks of the service switching points SSP and of the service control points SCP in an intelligent network is given on pages 105-117 of the book xe2x80x9cIntelligent Netzexe2x80x9d (xe2x80x9cIntelligent Networksxe2x80x9d) by Gerd Sigmund, published in 1999 by Hxc3xcthig Verlag, Heidelberg (ISBN3-7785-3908-6).
In this connection, the invention is not restricted to the intelligent network, but covers equivalent network operator""s facilities and processes by means of which value added services can be offered. The network operator today therefore offers a large number of specific services outside the intelligent network. For example, these services can be realized with the aid of additional functions in the digital switching centers. Since these functions are comparable to those of the intelligent network, the description below is limited to embodiments in the intelligent network.
While at the start the intelligent network was mainly installed and operated country wide and centrally by a national network operator, IN services are also increasingly being offered by other network operators. Many of these network operators are building their own network infrastructure to do this. A network operator""s infrastructure is regarded as an own intelligent network if the network operator is able to recognize and process service calls.
While the functions of the service switching points SSP are of a decentralized type, and today are usually integrated in every local switching center, the functions of service control points are of a centralized type. In this case, each service number existing in the national network beyond the limits of the respective network operator has to be resolved so that the call can either be switched to a specific physical address of a facility, or the network operator determined in whose intelligent network the service associated with the service number is performed. As a result, a subscriber can direct a service call to any desired network operator, irrespective of which network operator is performing the service. This transparency of service numbers in relation to the network operators is also termed service number portability (SNP). The service numbers and the associated data concerning addresses and network operators are usually stored in high-capacity databases of the service control point SCP. Here the service control point SCP of a large network operator is formed from a number of networked computers which communicate with each other for example via a so-called high-capacity local area network LAN.
This architecture is a problem for small, mostly local network operators which often cover only the area of a town. The operation and maintenance of a database for resolving all service numbers extending beyond their own service numbers would represent a disproportionately large outlay for many of these network operators. If one such network operator operates his own intelligent network without such a database, then in order to guarantee service number portability, initially he basically always has to relay all calls from IN services to a large national network operator who then resolves the call number.
To be able to execute service calls without rerouting via a national network operator and without needing to interrogate such a database, a process is conceivable in which service number portability is dispensed with and only service numbers of those IN services are resolved, which can be provided in the intelligent network of the called local network operator. Other (IN) service calls are cleared in reverse, that is to say these calls are cancelled. The subscriber then has to direct a repeat service call to another, preferably country-wide network operator. This process is of course less user-friendly and would probably severely reduce the acceptance of local IN services of this type. Furthermore, service number portability is a legal requirement in many countries.
Now the object of the invention is to create a process and suitable means that make it possible, in particular for local network operators, to perform IN services without rerouting via a further network operator and without the local network operator having to know the necessary service numbers of IN services that are not provided in his network.
This object is achieved according to the invention by a method for routing service calls in a telecommunication network, with a switching center recognizing the service call and a control facility controlling the service call, a telecommunication network with a switching center recognizing a service call of a subscriber and a control facility controlling the service call, a switching center with recognition means for recognizing service calls of a subscriber and communication means for exchanging messages with a control unit for controlling service calls and a program module to be executed in a switching center.
The fundamental idea of the invention is that always when the resolution of a service number is not possible with the aid of the local database, this call is passed to a further, preferably national network operator. In this case the network operator to whom the call is being transferred does not necessarily have to be the correct addressee of this service. It could be conceivable that this network operator also is unable to manage the complete resolution of the service number and further forwards the call.
Further developments of the invention are revealed in the description below.